by Jonathan Amos (BBC) Some close-quarter flying has provided new insights into aircraft pollution. — US space agency-led scientists flew small, instrumented, chase planes directly in the exhaust plume of a big jet to measure the sorts of gases and particles being thrown out.

The data suggests aircraft burning a mix of aviation kerosene and biofuel could reduce their climate impact.

This would come from a substantial reduction in the production of the sooty particles that make contrails.

“Those soot particles serve as nuclei for water vapour in the very cold atmosphere to condense on and for the artificial-looking linear contrails that we see when we look out the window,” explained Richard Moore from Nasa’s Langley Research Center.

“You’ll then see those lines spread and form cirrus clouds that weren’t there before the plane flew through the airspace.

“We know these contrails and cirrus clouds have a warming effect on the Earth’s climate, and it’s currently thought the warming effect associated with those clouds is more significant than all of the carbon dioxide emitted by aviation since the first powered flights began,” he told the Science In Action programme on the BBC World Service.